Motor-horn.



W. SPARKS.

MOTOR HORN.

APPLICATION FILED mvs. m3

Patent-ed Aug. 21, 1917.

UNITED WILLIAM SPARKS, 0F JAGKSONgMICHIGAH, ASSIGNOR; 'BYMFESNE-ASSIEGIFMIHN'IS, TO

SPARKS WIIHINGTON COMPANY, A" OORZBORAHON OF'OH'IO.

.:MOTOR-H-ORN'..

1 237,715 .--Spccification\o! Letters Patent. gmwbed:Amg;;21,i1Q1 7 Application aleair 6, 1913. Serial m 755,292.

It; all whom it may concern:

Be it known that I, WILLIAM SBanKs, of Jackson, in the county offJacksomin' the State of Michigan, have-invented new arid useful Improvements in Motor-Horns, of which the following, taken in connection with the accompanying drawings, is a full, clear, and exact description.

This invention relates to certain improvements in motor .hornsadapted' to be used as a signal or alarm for automoltfilespzmotor boats and similar machines. and comprises an electric motor attached to one end ofia diaphragm case containing a Vibratory-diaphragm having means thereon 'coiiperating w-itha motor-driven actuatorfor vibrating the diaphragm and thereby producing sounds which are amplified by-a megaphone attached to the other-en'dof the diaphragm case.

The main object is to increase the electrical efliciency of a two pole motor and; at the same time, to reduce its bulk by reducing the number of parts to such an extent as to allow the entire motor to be applied eccentrically to one end of a diaphragm case wholly within the area of the vibratory part thcrcofanrl toallow the use of a central contact or abutment on the diaphragm for c0- opcrative engagement by the motor-driven actuator.

-In other wordsxI have sought to produce a simple, light and powerful motor horniat a considerably lower cost of manufacture than has-heretofore been practised without sacrificing any of the advantages'of this class of horns.

Another object is to facilitate the adjustment of' the diaphragm actuator'for wear and volume of tone Without displacing any of the parts 011 the motor or sound-producing device.

Other objects and-uses will be broughtout in 'the following description.

In'the drawings-- Figure 1 is a side elerationof a motor horn embodying the various features of'my invention.

Fig.2 is an end view of the same.

Fig. 3 is an enlarged longitudinal sectional view axially through the motor and sound-producing device, together with the adjacent end of thesamplifier .taken online 335Fig. 1.

Figs. '4' andk'i' are transverse sectional views taken respectively on' lines an'd 5-5,'*Fig.' 1;

Fig; 6 is-a detail iriew of-the diaphragm actuator,- a portionof a diaphragm and one side of the case being shown 'inseetiou.

Fig. '7 is-a; perspective-view drone of the brush holders, midi-Fig. 8is a similar'perspective'view of one of the brushes.

EHeretdfore, sofar as Iam aware; the field magnets for motor horns of this-character have consisted of .1- cylindrical 'shell" coaxial with" the axis of the diaphragm and, therefore, excessively heav md subject togreater or less di$i pation of electric energy-wyhich proportionately weakened the fiieiency of the motor, but I have discovered that by constructing the motor in a manner hereinafter described, it may be materially reduced in "sizeand its power-efficiency greatly increased.

In order to accomplish these'reeultsfI have-provided atwo pole electric motorwith a field'magnet 1'-- consisting of a Ushape steelframe -"2 and castiron pole' pieces 3- which are firmly secured to the inner faces of'the opposite arms of the frame -'2-by screws 4-= hav'ing their' -h'efids countersunk in' the outer faces of=sa-id--arms as 'shown-more'clearly in'Figs. "3'and 5.

The frame 2- is preferably maide'of a single piece or str-i of-rolled orpressedsteel hailing diametrica; ly opposite, substantially parallel arms spaced apart a sufiicientdistance to receive between-the pole= pieces-am armature said arms being united=at one end by widlametrically extending cross bar -'6'-:-while their opposite ends-are bent toward each other in radial lines to form su-pportin feet 7 parallehwith and a suflicient iStance-apart fr-om thecross bar to receive the revolving parts of the motor.

The entire'frame 2 is, thereforeyof uniform thickness and preferably of uniform width 'from end t0 en'd,' the-width be ing usually the same as the pole/pieces '3- which are secured to the opposite arms, said arms being arcuate in cross section and concentric with the axis of the armature.

The cross bar -'-6- of the frame 2 is provided with a central aperture -8 and diametrically opposite arms -9 stamped inwardly therefrom parallel with the axis,

. adjusted by means ofa screw 16 in the outer end of the bushing and coaxial with the shaft for adjusting said shaft endwise to, compensate for wear or to vary the volume of tone of the soundproducmg device presently described.

. .The supporting arms 9- for the brush 'holders .10are integral with the cross bar --6 and are pressed inwardly beyond theplane of said cross bar to form openings 9' through which the lead wires, as +w, of the motor are extended and thence outwardly through an opening in an inclosing shell 17- which surrounds the motor to exclude .dust and other foreign matter therefrom and also to prevent malicious or accidental interference with the operation of themotor.

The opposite end of the shaft --13- is journaled in a suitable bushing 18 centrally in one of th case sections, as l9-, of the diaphragm case and is provided with an actuator 20- having a circular series of face teeth operating successively against an abutment 21- which is centrally secured to a circular diaphragm 22--, the latter having its marginal edge rigidly clamped between the marginal edge of the case section 19 and an opposed case section 23 forming the base of an amplifier 24-.

The feet -7 of the opposite arms of the motor frame -2 are secured by suitable fastening means, as screws 25, to the adjacent face of the section -19-- of the diaphragm case, said section being provided with an annular reinforcing rib 26- which also serves as a registering stop for alinin the motor frame coaxial with its shaft in assembling said frame upon the adjacent end of the diaphragm case.

The actuator 20- preferably consists of a disk tightly secured upon the adjacent end of the shaft between the case-section 19- and diaphragm so that by unscrewing the disk and removing the screws 25, the entire motor may be removed, the case section 23- being also screwed upon the periphery of the section 19, thus permitting the diaphragm to be removed when necessary or to gain access to the actuator or screws 25.

Surrounding the'pole pieces 3 are suitable field windings 3' which are electrically connected in the usual manner to the brush holders.

These brush holders are secured in suitable insulating bushin s 27- in the apertured arms 9- an are provided with lengthwise sockets open at their inner ends for receiving the brushes 11-, the latter being spring-pressed by springs 28- against the periphery of the commutator 1g It will be observed upon reference more particularly to Figs. 4 and 5 that the entire motor is secured to one end of the diaphragm case eoeentrically to the axis of said diaphragm a distance corresponding to the radius of the actuator 20- which allows the use of a contactymember 21-'- on the center of the diaphra thereby producing a maximum and unii gm degree of vibration of such dia hragm and aifording'deeper and more uni orm tones than is possible when the contact member is offset to'one side of the center.

The housing 17-- for the motor is cylindrical and has its open end tightly fitted upon a circular boss concentric with the axis of the diaphragm but eccentric to the axis of the motor as shown more clearly in Figs. 4 and 5 and its Outer end is closed and provided with a removable cap 30- pivoted at -31-- to swing transversely of the axis, but is held in its normal position by a catch 32-, said cap being apertured to permit the passage of the wire leads atherethrough and when moved from its normal position permits access to the adjusting screw 16- without disturbing any of the other parts of the motor or sound-producing device other than to adjust the actuator into proper coaction with its contact member 21-.

The armature of the motor is yieldingly held against excessive endthrust toward the diaphragm with its op osite end in contact with the ball bearin y means of a spring -40 extending diametrically across and around the armature shaft and having its ends bearing against the case section 19- and its central portion spring-tensioned against a bushing on said shaft, which bushingengages the adjacent end of the .armature core, as shown more clearly in Fig. 3.

It will be observed that the actuator for the diaphragm is also made of pressed sheet metal for economical reasons and also to afford a smoother and harder contact surface for the hardened contact member on the diaphragm than would be possible if made of cast metal.

I have previously stated that one of the objects of the invention is to increase the electrical ellicieney of the motor by making the field magnet in the form of a U-shape bar of cold rolled steel, while the pole pieces are preferably made of cast iron, but may be made of bar steel or other suitable magnetizablo metal separate from but rigidly secured to the opposite arms of the U-shape bar so as to complete the field magnet of the motor, the outer ends or faces of the polepieces being concentric with the axis of the motor shaft so as to form and fit snugly against the correspondingly curved sides of the U-shape bar and thereby establish close electrical connection therewith when the pole-pieces are secured thereto by the screws By constructing the motor frame in the manner just described including the polepieces, it is evident that the entire motor may be placed in a comparatively small compact space at one side of the center of the diaphragm or axis of the case 17- a distance corresponding to the radius of the toothed wheel for the purpose previously stated.

Another reason for this increased eiliciency is believed to lie in the fact that the magnetic bar is of approximately the same Width as the pole pieces and that this relative size reduces dissipation of energy to a minimum, because in the use of cylindrical shells with the same armature and field winding there appears to be a dissipation of energy resulting from the large area over which the magnetic current is distributed.

The main feature of this invention, therefore, resides in the use of a U-shaped magnetic bar, embracing the armature with the feet of its opposite arms secured to one end of a diaphragm case and its opposite end constituting a support for one end of the motor shaft, the latter having its opposite end journaled in the inner end of the diaphragm case and provided with an actuator and coooperating with a projection 011 the center of the diaphragm for imparting vibratory movement thereto.

In addition to these features, the inven tion also consists in making the U-shaped magnetic bar of substantially the same width as the pole pieces and in securing said pole pieces to the opposite arms of the U-shaped bar intermediate their ends, and in certain other minor features which will be brought out in the claim.

What I claim is:

A horn comprising front and rear case sections for a diaphragm, a diaphragm having its periphery secured between said case sections and its intermediate portion free to vibrate, a Wearpiece on the central portion of the diaphragm, a narrow thin sheet metal strip bent in U-shape form and having its ends secured to the rear case section to form a U-shape motor case, pole-pieces rigidly secured to the opposite sides of the motor case and projecting toward each other within the case, brushes carried by and within the case, an armature having its shaft journaled in the rear wall of the U-shape case and in the rear case section, a commutator on the shaft within the U-shape case, an actuator mounted on the shaft and adapted for contact with said wearpiece, and a casing inclosing the U-shape case and other motor parts.

In witness whereof I have hereunto set my hand this 23rd day of April, 1913.

WILLIAM SPARKS.

\Vitnesses H. E. CHASE,

EVA E. GREENLEAF.

Copies of this patent may he obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. C." 

